function flu = fluence(Ab)
[L,m,n]=size(Ab);
F=zeros(n,1);
Area=zeros(n,1);
for(i=1:1:n)
    for(j=1:1:m)
        for(k=1:1:L)
            if (Ab(k,j,i)~=0)
                F(i,1)=F(i,1) + Ab(k,j,i);
                Area(i,1) = Area(i,1) + 1;
            end
        end
    end
end
flu=F./Area;
    